Works with any amount of marchers, as long as you can tell that it's a cube, it'll be fine.
First you create 2 identical squares, you do this by using the CTRL C CTRL V shortcut. They both can be any size you want. Then connect each corner to its corresponding corner with any number of marchers. Now the fun part!
Making it look 3D:
First you move each square any amount of steps as you want, as long as it maintains it's shape, both squares go opposite direction in the same amount of steps to make it cleaner. you then rotate the connectors and connect them to each corner as you did before. MAKE SURE TO ROTATE THEM THE CORRECT WAY AS TO MATCH THE MOVEMENT OF THE SQUARES :)
You can do this as many times as you want. You can even try different shapes if you wish, just follow the same directions! The show should clarify a bit more but I hope you enjoy and use it wisely!
PS. my show The Grand Color Scheme shows how to use this perfectly, as well as how to set it up